Navigation computer



Sept. 24,1946. A. M. WOLFE NAVIGATION COMPUTER Filed July 6, 1944 INVENTOR. I

Patented Sept. 24, 1946 UNITED STATES PATENT OFFICE 16 Claims.

This invention relates to an improved air navigation computer, and moreparticularly to a computer constructed and adapted to be used in thenavigation of aircraft operating from an aircraft carrier. While myinvention is of particular advantage for such purposes, it will beunderstood, however, that its use is not limited thereto, and it may beadvantageously employed in solving navigation problems generally.

When operating an airplane from an aircraft carrier, the pilot must bealways on the alert for indications of the enemy, in the air, on thesurface, and under the water. He must also constantly watch for anyunusual objects on the surface, such as life rafts, boats, and the like.

In addition he must constantly check the instruments indicating theperformance of his own craft. All this must be done while carrying outhis orders, which may require flying over considerable distances whileout of sight of the carrier. It is, therefore, vital for him to be atall times absolutely certain of his own position and that of thecarrier, and to be able quickly to work out navigation problems, shouldemergencies develop requiring a change in his original flight plan.

His many duties other than navigation do not permit him to engage incomplicated and timeconsuming plotting methods for solving navigationalproblems, with the ever-present possibility of error due to inadvertenceor excitement. The navigation which he is required to do while flyingmust be done quickly and accurately, and withv out interference with hisother duties.

With the use of the computer according to my invention, the pilot isable to solve all necessary navigational problems easily and quickly,with a minimum possibility of error, and without the necessity of layingthe problem out in vector form on paper.

Among the objects of my invention may be mentioned the following:

' To provide a navigation computer particularly adapted for use bypilots of aircraft operating from aircraft carriers, and which willquickly solve vector problems without requiring the drawing of vectordiagrams.

To provide such a computer which will enable the pilot quickly tovisualize the problem, thus reducing the possibility of error.

To provide such a computer which is simple, positive, and reliable inoperation, light in weight, small in size, and inexpensive tomanufacture.

To provide a simple and accurate method of 2 solving navigation problemsinvolving relative movement.

To provide a navigation computer that will solve any complicated deadreckoning problems 5 as well as the simple.

To provide a computer that can be used direct on maps if desired.

Still other objects and advantages of my invention will be apparent fromthe specification.

The features of novelty which I believe to be characteristic of myinvention-are set forth with particularity in the appended claims. Myinvention itself, however, both as to its fundamental principles and asto its particular embodiments, will best be understood by reference tothe specification and accompanying drawing, in which Fig. 1 is a planview of a computer in accordance with my invention,

Fig. la is a detail section taken on line la-la, Fig. 1, partly insection, on an enlarged scale, of one of the joints of my computer,

Fig. lb is a detail View of one of the disks which may be used,

Fig. 1c is a detail View of one form of pivot I may use,

Fig. 1d is a detail view of a form of connection between two arms of mycomputer,

Fig. 2 is a side elevation of the computer of Fig. 1, partly'in section,and

Figs. 3a, 3b, 3c, and 3d show typical adjustments of my computer insolving navigation problems.

In accordance with'my invention, my computer may comprise a disk l0preferably, but not neci essarily, of transparent material, calibratedin degrees from true north from 0 clockwise to 360, and also, ifdesired, in reciprocals in smaller figures (in degrees from true southfrom 0 to 360 clockwise). Pivotally attached at the center W of the diskthere may be provided an extensile or telescoping arm H calibrated inair speed in knots or miles per hour.

Any suitable telescoping arrangement may be used, such, for example, asis employed in slide rules; but for economy of space, weight, andmaterials, I prefer to provide a channeled member lid of thin sheet,preferably non-magnetic, metal, or plastic, within which there may bemounted the calibrated slider I lb.

An indicator may be provided, such as an index pointer lie on the memberHa, so that as the arm I l is lengthened and shortened, the true airspeed may be read directly from the indicator. A screw clamp I id or anyother suitable arrangement may be provided for securing the arm I l atthe length to which it is adjusted. The arm II is preferably, but notnecessarily, mounted under the disk III.

A second arm I2 may'also be pivoted at the point W for rotation aboutsaid point as a center. This is preferably arranged so that it may berotated through 360 and a clamp such as screw I2a may be provided forsecuring it to the rim of disk III in the particular angular position towhich it maybe set. This arm I2 is preferably calibrated in knots ormlies per hour wind velocity.

It is preferable for arm I2 to extend past point W and to have the pivoton an offset bracket I2d as shown in Fig. lc for a reason which willbedescribed later.

A third arm I3 may be pivotally secured at point P to the outerextremity of arm I I, and to a point on a sliding sleeve IZb, slidableon the arm 'IZ. The offsetting of the pivot on bracket I2d permitssleeve I2b to slide past point W in case point E should fall directlyover point W. A clamp such as screw l2c may be provided for locking thearms against movement of point E after adjustment. The arm I3, like armI2, is extensile and is preferably made in two parts, I3a and I3b,telescoping one into the other, and may be calibrated in knots or milesper hour, and may have an index pointer I3c.

The ends of arm I3 may be slightly offset as indicated at I3e and I3) sothat the edge I3d may permit a pencil mark made against this edge to lieaccurately in the line connecting points E and P. This is desirable forsolving wind star problems. The otherarms II and I6 may have similarlyoffset ends if desired, and the arm II may project slightly beyond pointP to form a handle I Id for convenience of operation.

Also, secured to the disk III at point-W, and preferably, although notnecessarily, between it and the arm I I, and mounted for rotation, I mayprovide a second disk I4 preferably, but not necessarily, of transparentmaterial, which may be marked with a number of parallel lines, as at Ma,and with an indicating arrow, as at I Ib. This disk may also have adrift scale I40 and the letters L and R with appropriate arrows, asshown in Fig. 1b. The two disks Ill and I I and the three arms II, I2,and I3, are all that is necessary for solving simple problems.

For example, the length of the arm I I may indicate the true air speedand the angular position of the arm the true heading in degrees fromtrue north, the length of arm I3 the ground speed, the angular positionof arm I3 the true course, the length from W to E on arm I 2 the windvelocity, and the angular position of arm I2 the wind direction.

If the pilot knows his true heading and his true air speed, and the winddirection and velocity, he can quickly determine his true course andground speed, as follows: He will first set the arm I2 to the angularposition of the wind direction on scale I M, and lock it in position byclamp I 2a. The point E will then be moved along the arm I2 and set forthe wind velocity. He will then adjust the length of arm I I to readtrue air speed, and tighten the clamp I Id to hold the arm I I inadjusted length, Then he will swing point P until the angular positionof arm I I corresponds to his true heading as shown by scale I a.

The length of the arm I3 will then represent the ground speed of theairplane and may be read directly from pointer I30 off the scale on thearm I3. The direction of point P from point E will represent the truecourse. To read the direction of point P from point E in degrees, thenavigator rotates disk I4 until the lines I4a marked on it run parallelwith the arm EP (l3). Then the arrowhead I4b will point to the truecourse in degrees from true north.

It will be seen that if the true heading and air speed remain the sameand th wind changes velocity, as the point E is moved along arm I2 tothe new wind velocity, the arm I3 will increase or decrease in lengthand the direction of point P from point E will change. Similarly, shouldthe wind change its direction, as arm I2 is rotated to the newdirection, arm I3 will change correspondingly.

With the construction so far described, it is possible to find the truecourse, knowing the true heading as already described, or to find thetrue heading and air speed to be maintained for a given true course andground speed. In the latter case, one would set the wind direction andvelocity first, then adjust arm I3 to the direction of true course bysetting disk I4 to indicate true course, swing point P until arm I3 isparallel with the lines Ma, and then adjust the length of arm I3 forground speed of the airplane. The length of the arm I I will thenrepresent the air speed of the airplane, which may be read from thescale on arm I I, and the angle of the arm I I will represent the trueheading which must be maintained to make good the true course, and thismay be read directly from the scale Illa.

If it is desired to solve problems involving a surface ship, such as acarrier, as in a geographic sector search to a moving base, relativesector search, relative square search, fictitious ship, etc., additionalstructure will be provided. This may comprise the arm I5 pivoted atpoint E to the sleeve I2b or arm I2 and carrying a sleeve I5a havingclamp I5b, by which it may be secured to the periphery of disk III. Thisarm will be calibrated for the speed of the surface ship.

Arm I6, similar to arms II and I3, may also be provided, pivoted atpoints S and P, and this.

arm may comprise a pair of extensile, telescoping members Ilia an Hit)and may be calibrated in miles per hour or knots. The point S is madeadjustable along arm I5 by means of sleeve I50 and a clamp I5d may beprovided for holding the adjustment. Preferably, the connection betweenarms I5 and I6 at point S is made quick detachable as by ball I5e on armI6, engaging spring socket I5 on sleeve I50. This is necessary forcertain adjustments, as for instance when the airplanes course is thesame as the surface ships, when arm I3 would otherwise strik or jamatpoint S. It is desirable that the arms I3 and I6 be so arranged thatparts I31) and I61) be able to slide in parts I3a and I5a beyond thepivot points E and S respectively as indicated in Fig. 1d.

To set the surface ships course, the disk I4 will be rotated until thearrow Mb points to the ships course, clamp I 522 will be loosened, andthe arm I5 rotated about point E until it is parallel to the lines I la.It is then clamped in position. The point S will then be adjusted alongarm I5 until it is at the position of the surface ships speed, and thenclamped in position. Then the angular position of arm I6 will representthe direction of relative movement, and the length of arm IS the speedof relative movement. The former may be read from scale Illa by rotatingdisk I4 until the lines on it are parallel to arm I6, and the latterread from the scale on arm I6.

Under som conditions it'may be desirable to disconnect sleeve Ia fromthe rim of disk I0, and to clamp it at the end of arm I2. This may beeasily and quickly done by providing an extension on the clamp I2a ofapproximately the same thickness as disk I0. Other ways in which thismay be done will be readily apparent. This is necessary if the surfaceshipscourse is the reciprocal of the winds direction, in order to letarm I5 fall directly over arm I2.

It will be observed that the arms II, I3, and I6 are all pivoted at thecommon point P. Any shift in point P circumferentially will change thedirection of all three arms, and the length of the arms I3 and I6 whenarm II is locked at IId. If armII is unlocked at it, any movement ofpoint P in a radial direction will change the length of arms II, I3, andI6, and the direction of arms I3 and I 5. Some typical ad- J'ustedpositions of my computer, as used in solving navigational problems, areshown in Figs. 3a to 3d inclusive, and it will be noted that in everycase shown in these figures there are two triangles having one sidecommon. These triangles may lie one within the other, may partlyoverlap, or may be without overlap.

Wind stars may also be worked with my computer. To facilitate this, Iprefer to frost the center of the disk III in the circle I0b so that apencil mark may be made upon it. I may also attach a small tab I Ie offrosted plastic or other material to arm I I so that the compassvariation may be'written on it, for convenience in correction of trueheading to magnetic heading or vice versa.

The following is an example of how a wind star problem is worked with mycomputer:

While flying on a true heading of 061 at a true air speed of 125 k. thepilot notes a drift of 14 R. To set this up he swings arm II (or W-P)*until it reads 061 on scale I0a of disk I0 and adjusts the length of armI I to true air speed of' 125 k. He then revolves disk I4 until I Ibreads061 or the parallel lines (Ila) run parallel with arm II. Thensince the drift is 14 R, he moves disk I4 to the right for 14 or thepointer III) to 075 (061+14=075). Then he adjusts point E of arm I3(E-P) until it is parallel to the lines on disk I4 and draws a linealong edge I3d of arm I3 on the frosted area of disk III. He repeats theabove operation for the following two headings:

True heading 121", true air speed 125 k., drift True heading 001", trueair speed 125 k., drift From the above operation he will have threelines drawn on the frosted area of disk I0. These three lines will allcross and establish a point. From this point to W will be the directionthe wind is blowing and the distance from this point to W will be thevelocity. The wind in this case is from 340' with a velocity of 30 k.

In a relative square search a relative wind must be determined. For thispurpose the radius of disk I I extending to point IAb will preferably becalibrated in terms of relative wind velocity. In working problemsinvolving relative wind, the disk It may be revolved until the radius topoint Ilb lines up with points W and S.

In the above disclosure I have explained the problems with the windplotted up-wind; that is, from E to W. The problems, however, may beplotted, down-wind; that is, with the wind blow- 6 ing from W to E, andif that is done, then the arm I3 will represent the true heading and airspeed instead of true course and ground speed, and the arm II will thenrepresent the true course and ground speed.

A solution of a typical problem involving an airplane and a surface shipwill now be given, explaining the use of my computer.

Suppose a relative sector search is to be made from an aircraft carrier.The position of the carrier may, for example, be at 0800, latitude 41 4'north, longitude 52 4 west, course 160, speed 25 knots. The pilot'sorders are to depart from carrier at 0800, search a relative sector from60 to for 120 miles, returning to carrier; flight level 2,000 feet, trueair speed knots, temperature 45 C., wind from 034, force 20 knots.

The pilot must determine, from the data given, the true heading to bemaintained, speed of relative movement, true course, distance covered,and ground speed for each of the three legs of the search, and the timefor making each turn required to fly the course.

Since the back leg of the search will always be flown first, the pilotwill solve for the back le first. This may be done by first setting thearm I2 to the wind direction 034 and setting point E to the windvelocity. Arm I5 will then be adjusted for the course of the carrier,160, and the point S will be set at the speed of the carrier.

The length of arm H will then be set at true air speed, 110 knots, and.the angular position of arm I 6 will be set for the direction ofrelative movement, 60. With this setting the length of arm I3 will thenbe the ground speed, 94 knots, Cus. 75, and the angular position of armII the true heading, 685.

When the course and speed of the carrier, the wind direction andvelocity, the true air speed, and the direction of relative movement,which are known, are set, the ground speed, 94 knots, may be determinedby reading the scale on arm I3; the true course, 75, by reading theangular position of arm I3 on scale Illa through the use of disk I4; thetrue heading 68.5", from the an-- gular position of arm II; and thespeed of relative movement between airplane and carrier, 95.5 knots, maybe read from arm IS. The time for making the turn to the second leg ofthe course is determined by dividing miles by the speed of relativemovement, and is 75.5 minutes.

The distance covered on this leg is ground speed multiplied by time, andis 118 miles.

To solve for the second leg, it is first necessary to find the truecourse and distance of this leg and true heading. This is found, in thecase given, to be 164 and the distance 7'7 miles. In setting thecomputer, since wind direction and velocity, true air speed, and surfaceships course and speed are unchanged, it is only necessary to swingpoint P until arm I6 has the angular position of the direction ofrelative movement of the second leg. The new direction, 165, and speedof relative movement, 97 knots, ground speed, 122 knots, and trueheading, 156, may now/be read'as before, and the time, 38 minutes, formaking the second turn obtained.

The third leg may be solved for in the same way, by swinging point Puntil arm I6 reaches 270, the given direction of relative movement forthe third and last leg. From arm I3, true course is found to be 259, andground speed 123 knots; from arm I I true heading is 266, and from armI6 speed of relative movement is knots. Knowingthe distance to thepoint'of interception with the carrier to be 120 miles of relativemovement, the time of the last leg is found to be 55.5 minutes and thetime of interception 10:49. It will be apparent thatthe method which Iemploy makes a vectorial solution, but the vectors are, not lines, butthe arms ll, I3, l6, I2, and I5, and since these are all connected atthe proper points and: arranged .in proper relation to each other, thereis no possibility of error due to incorrect laying out of .the vectors,as in a solution worked out on paper, or in the length of each arm orvector since it is read direct.

While I have shown and described certain preferred embodiments of myinvention, it will be understood that modifications and changes may bemade without departing from the spirit and scope thereof, as will .beclear to those skilled in the art.

I have particularly pointed out and distinctly claimed the part,improvement, or combination which I claim as my invention or discovery,and in the specification I have explained the principles thereof and thebest mode in which I have contemplated applying those principles so asto distinguish my invention from other inventions- I claim: a

1. A navigation computer comprising, in com.- bination, a. compass rose,an extensile arm pivotally secured for rotation to the center of saidcompass rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass rose forrotation, said second arm carrying a scale indicating wind velocity, anda second extensile arm pivoted atone end to the outer end of the firstextensile arm and at the other end to an adjustable point on said secondarm, said third arm carrying a. scale indicating speed.

2. A navigation computer comprising, in combination, a compass rose, anextensile arm pivotally secured for rotation to the center of saidcompass. rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass rose forrotation and having means forfixing its'adjusted angular position,said'second arm having a scale indicating wind velocity, and a secondextensile arm having one end pivoted to the outer endof the firstextensile arm and the other end slidably and pivotally mounted upon saidsecond arm, said second extensile'arm carrying a scale indicating speed.Y Y

3. A navigation computer comprising, in combination, a compass rose, atelescoping arm pivotally secured for rotation to the center of saidcompass rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass rose forrotation, said second arm having a scale indicating wind velocity, and asecond telescoping arm having one end pivoted to the outer end of thefirst telescoping arm and the other end adjustably and pivotally mountedupon said second arm said second telescoping, carrying a scaleindicatingspeed.

4.- A navigation computer comprising, in combination, a compass rose, afirst arm comprising two parts slidable on each other and pivotallysecured for rotation to the center of said compass rose, said arm beingprovided witha scale indicating speed, a second arm. pivotally-securedto the center of said compass rose for rotation, said second armcarrying a scale indicating. wind velocity, and a third arm comprisingtwo parts slidable on each other pivoted at one end to the outer endofthe first arm and at the other endto an adjustable point on saidsecondarm, said third arm carrying a scale indicating speed.

5. A navigation computer comprising, in combination, a compass rose,afirst arm and a second arm pivotally secured for rotation to the centerof said compass rose, a third arm pivotally connected between the outerend of the first arm and an adjustablev point on the second arm, afourth arm having one end pivotally secured to the connection betweenthe second and third arms, and a fifth armhaving one endv pivotallyconnected to the connection between the first and third arms, and itsother end pivotally. connected to an adjustable point on said fourtharm; said first, third, and fifth arms being extensile, and all of saidarms carrying speedindicating scales.

. 6. The combination claimed in claim 5, with means for locking theadjustment of one or more of the following: the length of the first arm,the angular position of the second arm, the point of connection of thethird and fourth arm to the second arm, the angular position of thefourth arm, and the point of connection of the fifth arm to the fourtharm.

7. A navigation computer comprising, in combination, a compass rose,first and second arms pivotally secured to the center of said compassrose for rotation, third, fourth, and fifth arms pivotally securedtogether to form a triangle having one vertex pivotally secured to theouter end of the first arm, and a second vertex secured to an adjustablepoint on said second arm, the length of all three sides of said trianglebeing adjustable, and the length of the first arm and of two arms ofsaid triangle being adjustable intermediate their pivot points.

8. A navigation computer comprising, in combination, a compass rose,first and second arms pivotally secured to the center of said compassrose for rotation; third, fourth, and fifth arms pivotally securedtogether to form a triangle having one vertex pivotally secured to theouter end of the first arm, and-a second vertex secured to an adjustablepoint on said second arm, th length of' all three sides of said trianglebeing adjustable, and the first arm and two arms of said triangle beingextensile.

9. A navigation computer comprising, in combination, a compass rose,first'and second arms pivotally secured to the center of said compassrose for rotation, third, fourth, and fiftharms pivotally securedtogether to form a triangle having one vertex pivotally secured to theouter end of the first arm, and a second vertex secured to an adjustablepoint on said second arm to form a pair of triangles having one sidecommon, the length of all three sides of both said triangles beingadjustable, and two arms of each triangle being extensile.

10. A navigation computer comprising, in combination, a compass rose, anextensile arm pivotally secured for rotation to the center of saidcompass rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass roseforrotation, said second arm carrying a scale indicating Wind velocity, asecond extensile arm pivoted at one end to the outer end ofthe firstextensile arm and at the other end to an adjustable point on said secondarm, said-third arm carrying a scale; indicating speed, and a diskpivotally se' cured-to the center ofsaidcompass rose for rotation, saiddisk beingprovidedwith a pointer,

9 and a plurality of lines thereon parallel to said pointer.

11. The combination claimed in claim 10, in which said disk is oftransparent material.

12. The combination claimed in claim 10, in which said compass rose isof transparent material having a center frosted area.

13. The combination claimed in claim 10, in which said disk is oftransparent material and carries a wind velocity scale.

14. A navigation computer comprising, in combination, a compass rose, anextensile arm pivotally secured for rotation to the center of saidcompass rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass rose forrotation, said second arm carrying a scale indicating wind velocity, anda second extensile arm pivoted at one end to the outer end of the firstextensile arm and at the other end to an adjustable point on said secondarm, said third arm carrying a scale indicating speed, the connection atthe disk end of one of said extensile arms being quick detachable.

15. A navigation computer comprising, in combination, a compass rose, afirst arm and a second arm pivotally secured for rotation to the centerof said compass rose, a third arm pivotally connected between the outerend of the first arm and an adjustable point on the second arm, a fourtharm having one end pivotally secured to the connection between thesecond and third arms, and a fifth arm having one end pivotallyconnected to the connection between the first and third arms, and itsother end pivotally connected to an adjustable point on said fourth arm;said first, third, and fifth arms Ibeing extensile, and all of said armscarrying speed-indicating scales, and the second arm having means at itsouter end to which the fourth arm may be secured.

16. A navigation computer comprising, in combination, a compass rose, anextensile arm pivotally secured for rotation to the center of saidcompass rose, said arm being provided with a scale indicating speed, asecond arm pivotally secured to the center of said compass rose forrotation, said second arm carrying a, scale indicating wind velocity,and a second extensile arm pivoted at one end to the outer end of thefirst extensile arm and at the other end to an adjustable point on saidsecond arm, said third arm carrying a scale indicating speed, at leastone of said extensile arms having its pivots ofiset in line with oneedge thereof.

ASHER M. WOLFE.

